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When Ashton Kutcher is deciding which technology startups to throw his money at, he sometimes thinks about pilgrims.

"What would happen if a pilgrim would have seen seen a computer in action in Massachusetts back in the day?" Kutcher said onstage at a technology conference on Tuesday. "They probably would have killed that person and called them a witch because ultimately they would have seen it as magic."

In an analogy-laden interview at the TechCrunch Disrupt conference here, Kutcher described how he picks from the myriad small companies that appeal to him for cash. The "Two and a Half Men" actor has emerged as a prominent investor in Silicon Valley startups, lending his own money as well as money from his investment firm called A-Grade Ventures. He was also a celebrity early adopter of Twitter.

"We're all kind of on a witch hunt, really," said Kutcher, appealing to the other venture capitalists in the room. "I like to learn how magic tricks work."

Kutcher is considered a flashy outsider in many circles here but is quickly finding friends among entrepreneurs trying to catapult off of his celebrity. He bills himself as a seasoned marketer, as a former model who was able to launch an acting career and sell movies to high-profile producers.

He has lent financial and promotional support to Airbnb, the room rental listings service; Flipboard, the iPad news aggregator that CNN's Zite competes with; Foursquare, the location check-in application; and others. He said he sometimes hides his affiliation with companies to avoid overshadowing them.

"Disclosing that I'm an investor can sometimes be detrimental to the company," Kutcher said. "I try not to talk about until the company has a public awareness that's large enough and their story has matured enough so it won't be disruptive to the company."

This strategy got him into some trouble recently, when he edited a section of Conde Nast's Details magazine in which he promoted tech companies he was financially involved in without disclosing his relationships. The U.S. Federal Trade Commissions has rules about journalistic disclosure, but it said last month that it does not plan to investigate the matter.